From: Yu Zhang <[email protected]> Sent: Friday, September 4, 2026 12:55 AM > > Add page-selective IOTLB flush using HVCALL_FLUSH_DEVICE_DOMAIN_LIST. > This hypercall accepts a list of (page_number, page_mask_shift) entries, > enabling finer-grained IOTLB invalidation compared to the domain-wide > HVCALL_FLUSH_DEVICE_DOMAIN used by hv_iommu_flush_iotlb_all(). > > hv_iommu_calc_flush_range() computes the smallest power-of-two aligned > range that covers the target IOVA region, producing a single flush > descriptor. This may over-flush when the range is not naturally aligned, > matching the approach used by Intel VT-d PSI. If the page-selective > flush fails, the code falls back to a full domain flush. > > Signed-off-by: Easwar Hariharan <[email protected]> > Signed-off-by: Yu Zhang <[email protected]> > Reviewed-by: Jacob Pan <[email protected]>
Reviewed-by: Michael Kelley <[email protected]> > --- > drivers/iommu/hyperv/hv-iommu-guest.c | 74 ++++++++++++++++++++++++++- > include/hyperv/hvgdk_mini.h | 1 + > include/hyperv/hvhdk_mini.h | 18 +++++++ > 3 files changed, 92 insertions(+), 1 deletion(-) > > diff --git a/drivers/iommu/hyperv/hv-iommu-guest.c b/drivers/iommu/hyperv/hv- > iommu-guest.c > index 137f232d74fe..13eb85b4a424 100644 > --- a/drivers/iommu/hyperv/hv-iommu-guest.c > +++ b/drivers/iommu/hyperv/hv-iommu-guest.c > @@ -384,11 +384,82 @@ static void hv_iommu_flush_iotlb_all(struct iommu_domain > *domain) > hv_flush_device_domain(to_hv_iommu_domain(domain)); > } > > +/* > + * Calculate the minimal power-of-two aligned range that covers [start, end] > + * (end is inclusive). Returns a single (page_number, page_mask_shift) > + * descriptor that may over-flush when the range is not naturally aligned. > + */ > +static void > +hv_iommu_calc_flush_range(unsigned long start, unsigned long end, > + union hv_iommu_flush_va *va) > +{ > + unsigned long aligned_start; > + unsigned int sz_lg2; > + > + sz_lg2 = max(fls_long(start ^ end), HV_HYP_PAGE_SHIFT); > + > + /* > + * A valid IOVA range shall not span bit 63. Use the maximum mask > + * so the host can safely perform a full flush. > + */ > + if (WARN_ON_ONCE(sz_lg2 == BITS_PER_LONG)) > + aligned_start = 0; > + else > + aligned_start = > + start & GENMASK(BITS_PER_LONG - 1, sz_lg2); > + > + va->page_number = aligned_start >> HV_HYP_PAGE_SHIFT; > + va->page_mask_shift = sz_lg2 - HV_HYP_PAGE_SHIFT; > +} > + > +static void hv_flush_device_domain_list(struct hv_iommu_domain *hv_domain, > + struct iommu_iotlb_gather *iotlb_gather) > +{ > + u64 status; > + unsigned long flags; > + struct hv_input_flush_device_domain_list *input; > + > + local_irq_save(flags); > + > + input = *this_cpu_ptr(hyperv_pcpu_input_arg); > + /* Clear the fixed header and the single range entry. */ > + memset(input, 0, struct_size(input, iova_list, 1)); > + > + input->device_domain = hv_domain->device_domain; > + input->flags |= HV_FLUSH_DEVICE_DOMAIN_LIST_IOMMU_FORMAT; > + hv_iommu_calc_flush_range(iotlb_gather->start, iotlb_gather->end, > + &input->iova_list[0]); > + > + status = hv_do_rep_hypercall(HVCALL_FLUSH_DEVICE_DOMAIN_LIST, > + 1, 0, input, NULL); > + > + if (WARN_ONCE(!hv_result_success(status), > + "HVCALL_FLUSH_DEVICE_DOMAIN_LIST failed: %#llx (%s)\n", > + status, hv_result_to_string(status))) { > + /* Page-selective flush failed, fall back to full flush. */ > + struct hv_input_flush_device_domain *flush_all = (void *)input; > + > + memset(flush_all, 0, sizeof(*flush_all)); > + flush_all->device_domain = hv_domain->device_domain; > + status = hv_do_hypercall(HVCALL_FLUSH_DEVICE_DOMAIN, > + flush_all, NULL); > + WARN(!hv_result_success(status), > + "HVCALL_FLUSH_DEVICE_DOMAIN fallback also failed: %#llx > (%s)\n", > + status, hv_result_to_string(status)); > + } > + > + local_irq_restore(flags); > +} > + > static void hv_iommu_iotlb_sync(struct iommu_domain *domain, > struct iommu_iotlb_gather *iotlb_gather) > { > - hv_flush_device_domain(to_hv_iommu_domain(domain)); > + hv_flush_device_domain_list(to_hv_iommu_domain(domain), iotlb_gather); > > + /* > + * The hypercall also invalidates non-leaf page-walk caches, so > + * detached page-table pages can now be freed. > + */ > iommu_put_pages_list(&iotlb_gather->freelist); > } > > @@ -440,6 +511,7 @@ static struct iommu_domain > *hv_iommu_domain_alloc_paging(struct device *dev) > > cfg.common.hw_max_vasz_lg2 = hv_iommu_device->max_iova_width; > cfg.common.hw_max_oasz_lg2 = 52; > + cfg.common.features |= BIT(PT_FEAT_FLUSH_RANGE); > /* > * Hyper-V S1 domains use a 4-level root for IOVA widths up to > * 48 bits. A 5-level root is used only for wider apertures when > diff --git a/include/hyperv/hvgdk_mini.h b/include/hyperv/hvgdk_mini.h > index 5d1338197eee..966945f0504f 100644 > --- a/include/hyperv/hvgdk_mini.h > +++ b/include/hyperv/hvgdk_mini.h > @@ -497,6 +497,7 @@ union hv_vp_assist_msr_contents { /* > HV_REGISTER_VP_ASSIST_PAGE */ > #define HVCALL_GET_GPA_PAGES_ACCESS_STATES 0x00c9 > #define HVCALL_CONFIGURE_DEVICE_DOMAIN 0x00ce > #define HVCALL_FLUSH_DEVICE_DOMAIN 0x00d0 > +#define HVCALL_FLUSH_DEVICE_DOMAIN_LIST 0x00d1 > #define HVCALL_ACQUIRE_SPARSE_SPA_PAGE_HOST_ACCESS 0x00d7 > #define HVCALL_RELEASE_SPARSE_SPA_PAGE_HOST_ACCESS 0x00d8 > #define HVCALL_MODIFY_SPARSE_GPA_PAGE_HOST_VISIBILITY 0x00db > diff --git a/include/hyperv/hvhdk_mini.h b/include/hyperv/hvhdk_mini.h > index 7b9f43b320cd..57b70efe60d4 100644 > --- a/include/hyperv/hvhdk_mini.h > +++ b/include/hyperv/hvhdk_mini.h > @@ -685,4 +685,22 @@ struct hv_input_flush_device_domain { > u32 reserved; > } __packed; > > +union hv_iommu_flush_va { /* HV_IOMMU_GVA_RANGE */ > + u64 as_uint64; > + struct { > + u64 page_mask_shift : 6; > + u64 reserved : 6; > + u64 page_number : 52; > + }; > +} __packed; > + > +/* HV_INPUT_FLUSH_DEVICE_DOMAIN_LIST */ > +struct hv_input_flush_device_domain_list { > + struct hv_input_device_domain device_domain; > +#define HV_FLUSH_DEVICE_DOMAIN_LIST_IOMMU_FORMAT BIT(0) > + u32 flags; > + u32 reserved; > + union hv_iommu_flush_va iova_list[]; > +} __packed; > + > #endif /* _HV_HVHDK_MINI_H */ > -- > 2.52.0 >
